Pall cast over 2014 Games
Suicide attacks that killed 40 on the Moscow metro last month have fuelled fears Islamists will target the 2014 Winter Olympics, to be staged in the mountain range where the militants have their strongholds.
Soon after the Black Sea resort town of Sochi won in its bid to host the games, insurgents vowed in a statement to "attack any of the so-called 'Olympic participants' who represent the country's war against Muslims".
A year later, in 2008, a bomb exploded in Sochi and another in nearby Adler, each killing a civilian.
The deaths were celebrated by Islamist rebels from Russia's North Caucasus region, who want to create a pan-Caucasus sharia state independent from Russia, a struggle whose foundation was laid over 250 years ago.
They derailed the Moscow-St Petersburg Nevsky Express train in November, killing at least 26, and struck in Moscow in March, killing 40 and striking fear into the capital.
Sochi, hosting the ice-based Olympic events, and Krasnaya Polyana, 50 km (30 miles) inland where the snow sports will be held, are alarmingly close to Russia's restive provinces.
The Chechen capital Grozny is just 155 km (250 miles) to Sochi's west.
"Sochi's geographical proximity to these regions means that it will be potentially easier for them (insurgents) to travel to this area and the high-profile nature of the event itself means it's a tempting target," Matthew Clements, Eurasia analyst at IHS Jane's Information Group in London, told Reuters.
Islamist insurgents view Sochi, which belongs to the mainly Christian Krasnodar region, as "occupied territory", and some want it incorporated within the separate state they want to forge, according to unofficial Islamist websites.
Sochi residents fear their coastal town could become a target even before tight Olympic security is imposed.
"The word Sochi now means Olympics. The feeling here is it could happen any day. It's freaky," said 32-year-old history teacher Arman.
Deputy Prime Minister Dmitry Kozak, appointed by government to oversee the games, conceded last week in Krasnaya Polyana that the insurgency posed a threat.
"We are working hard on preventing terrorist attacks ... a comprehensive plan is being implemented," he said.
The head of the coordination commission for the International Olympic Committee, Jean-Claude Killy, said he had met high-ranking Russian security officials to discuss the issue.
Speaking in a plush new hotel nestled in a valley among the snow-capped mountains, he told reporters: "Those measures that are already in place will be augmented."
Compared to the turbulent trio of Chechnya, Ingushetia and Dagestan, on the southeastern slopes of the the craggy, chestnut and pine-covered Caucasus range, the Krasnodar region has seen little violence.
Across those Muslim regions, militants have carried out 23 attacks, mostly shoot-outs and suicide bombs, killing at least 34 people since the start of the year, compared to 17 in the same period of 2009, according to global intelligence firm Stratfor. Dozens of insurgents have also been killed.
Independent analysts Business Monitor International said in a report that the possibility of Russia losing de facto control of the situation in the North Caucasus could not be ruled out, "raising fears about the safety of the 2014 Winter Olympics".
Risks from Islamist extremism could also cloud Russia's World Cup bid for later in the decade, which might use Sochi's sleek new Olympic stadium, as well as efforts by Formula One supremo Bernie Ecclestone to take motor sport to Sochi.
Kozak said that Russia's sea and land borders would be strengthened ahead of the Games, in a nod to another potential hotspot 20 km (12 miles) to Sochi's south -- Georgia's breakaway region Abkhazia, which threw off Tbilisi's control in a war in the early 1990s.
Russia recognised the lush strip of Black Sea coast - once the playground of the Soviet elite - as independent in 2008 after Moscow repelled a Georgian assault on the country's other rebel territory, South Ossetia.
Georgia says the Olympics should be moved from Sochi.